Clinical tools such as physical exam, and CNS imaging (CT Scan or MRI) are subjective, not widely available, not sensitive or specific enough and too costly to identify the infant, child or adult with CNS injury. This can include individuals on life support or cardiopulmonary bypass, trauma, loss of oxygen, etc, regardless of the initial injury or disease. There is a great clinical need to identify patients with CNS or brain injury and especially subclinical injury because these infants, children and adults are at significant risk of progressing to overt stroke and development of cognitive and motor loss, dementia and poor mental performance. In addition, accurate and sensitive identification of CNS injury by circulating biomarkers will provide an objective gold standard to test and compare new therapeutic modalities for efficacy.